Composite electronic components

ABSTRACT

A dielectric coating ( 3 ), a solid electrolytic layer ( 4 ) and a collector layer ( 5 ) are provided to one face of a porous valve metal sheet ( 1 ). An insulating section ( 7 ) covers overall this metal sheet ( 1 ) including the layers ( 3, 4, 5 ) discussed above. Conductive bodies ( 101, 111 ), which are coupled with a first connecting terminal ( 2 ) and a second connecting terminal ( 6 ) respectively, are surfaced on at least one face of the insulating section ( 7 ). Connecting bumps ( 12 ) are formed on these conductive bodies ( 101, 111 ), so that ICs ( 17 ) and other parts are coupled with these bumps ( 12 ). This structure realizes a thin composite electronic component excellent in high-frequency response.

TECHNICAL FIELD

[0001] The present invention relates to a composite electronic component to be used in various electronic apparatuses.

BACKGROUND ART

[0002] A conventional composite electronic component comprises an integrated circuit (IC), a capacitor, an inductance, a resistor placed on a circuit board. In such a conventional composite electronic component, a capacitor is mounted on a circuit board as a solid electrolytic chip-capacitor in the same manner as other parts such as resistors and inductance parts.

[0003] Electronic circuits have been digitized recently in response to the market's demand, and this tendency involves high-frequency responses of electronic parts. A wiring is usually accompanied by a resistance component and an inductance component, and those components have not been raised as a problem, however, they now block the solid electrolytic capacitor, which is surface-mounted on a circuit board together with an IC, from fast responding to a high-frequency.

SUMMARY OF THE INVENTION

[0004] The present invention aims to overcome the foregoing drawback and provide a thin composite electronic component being excellent in high-frequency response and being bump-connectable to an IC directly. The composite electronic component of the present invention comprises the following elements:

[0005] a capacitor element;

[0006] an insulating section for covering the capacitor element;

[0007] a connecting terminal, provided to at least one face of the insulating section, for electrically coupling with the capacitor element;

[0008] a plurality of wiring patterns, provided to the same face as the connecting terminal, for conducting with electronic components; and

[0009] outer terminals, provided to lateral faces of the insulating section, for electrically coupling with the capacitor element.

[0010] The capacitor element includes the following elements:

[0011] a first connecting terminal provided to porous valve metal sheet which has dielectric coating on both its surface and the inner wall of its void holes;

[0012] a second connecting terminal provided to the porous valve metal sheet via a solid electrolytic layer at the face opposite to the first connecting terminal;

[0013] holes at least communicating with the first connecting terminal and the second connecting terminal, the hole having an insulating film on its inner wall; and

[0014] conductive bodies formed in the holes, and the conductive bodies being electrically connected with the first and second connecting terminals but insulated from other sections.

[0015] The connecting terminals are thus formed on the surface of the thin capacitor, and various chip parts including an IC can be mounted via the connecting terminals, so that high-frequency response is substantially improved. At the same time, the composite component is downsized and thinned.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0016]FIG. 1 shows a sectional view of a composite electronic component in accordance with an exemplary embodiment of the present invention.

[0017]FIG. 2 shows an enlarged sectional view illustrating an essential part of the composite electronic component in accordance with an exemplary embodiment of the present invention.

[0018]FIG. 3 shows a sectional view of a porous valve metal sheet to be used in the composite electronic component shown in FIG. 1.

[0019]FIG. 4 shows a sectional view of the porous valve metal sheet on which a first connecting terminal is formed.

[0020]FIG. 5 shows a sectional view of the porous valve metal sheet, shown in FIG. 4, where an insulating section is additionally formed on the sheet including the first connecting terminal.

[0021]FIG. 6 shows a sectional view of the porous valve metal sheet, shown in FIG. 5, where a dielectric coating and a solid electrolytic layer are additionally formed.

[0022]FIG. 7 shows a sectional view of the porous valve metal sheet, shown in FIG. 6, where a collector layer is additionally formed.

[0023]FIG. 8 shows a sectional view of the porous valve metal sheet, shown in FIG. 7, where holes are additionally formed.

[0024]FIG. 9 shows a sectional view of the porous valve metal sheet, shown in FIG. 8, where a second connecting terminal is additionally formed.

[0025]FIG. 10 shows a sectional view of the porous valve metal sheet, shown in FIG. 9, where an insulating section is additionally formed including the second connecting terminal.

[0026]FIG. 11 shows a sectional view of the porous valve metal sheet, shown in FIG. 10, where insulating film is formed in the holes.

[0027]FIG. 12 shows a sectional view of the porous valve metal sheet, shown in FIG. 11, where holes are additionally provided to the insulating section on the first connecting terminal.

[0028]FIG. 13 shows a sectional view of the porous valve metal sheet, shown in FIG. 12, where a conductive body is formed in the respective holes.

[0029]FIG. 14 shows a sectional view of the porous valve metal sheet, shown in FIG. 13, where a connecting bump is additionally provided to the respective conductive bodies.

[0030]FIG. 15 shows a sectional view of the porous valve metal sheet, shown in FIG. 14, where outer terminals are additionally provided.

[0031]FIG. 16 shows a sectional view of the porous valve metal sheet, shown in FIG. 15, where a wiring pattern is formed and electronic parts and ICs are mounted thereon.

[0032]FIG. 17 shows a sectional view of a porous valve metal sheet in accordance with a second exemplary embodiment of the present invention.

[0033]FIG. 18 shows a sectional view of a porous valve metal sheet in accordance with a third exemplary embodiment of the present invention.

DETAILED DESCRIPTIONS OF EXEMPLARY EMBODIMENTS

[0034] The exemplary embodiments of the present invention are demonstrated hereinafter with reference to the accompanying drawings. The drawings illustrate essential parts of the invention in order to demonstrate points of the invention, therefore, dimensions of the elements are scaled down differently from the actual ones.

[0035] Exemplary Embodiment 1

[0036]FIG. 1 shows a sectional view of a composite electronic component in accordance with the first exemplary embodiment of the present invention. FIG. 2 shows an enlarged sectional view illustrating an essential part of the composite electronic component.

[0037] Electronic component 16 shown in FIG. 1 has a thickness of the order of several millimeters, on the other hand, solid electrolytic capacitor element 200 has a thickness of the order of sub-millimeters. FIG. 1 enlarges, in particular, the capacitor element. An etched section has actually a complicated irregular shape on its surface; however, simplified pits are shown in FIG. 2 instead.

[0038] The composite electronic component shown in FIG. 1 and FIG. 2 comprises the following elements:

[0039] (a) porous valve metal sheet 1 made from aluminum foil of which one face is etched, or made of sintered body of valve metal powder such as tantalum; and

[0040] (b) first connecting terminal 2 provided to one face of sheet 1. In the case of aluminum foil being used, the unetched face can be utilized as first connecting terminal 2, or a layer of another metal such as gold, copper or nickel can be formed on the unetched face of the aluminum foil. In the case of the sintered body of the valve metal powder being used, a face to which the sintered body is mounted and no dielectric coating is formed can be utilized as first connecting terminal 2, or a layer of another metal such as gold, silver, nickel or tantalum can be formed by a spattering method or a vapor deposition method.

[0041] Anodizing the porous valve metal sheet 1 except first connecting terminal 2 forms dielectric coating 3 on the metal surface. Solid electrolytic layer 4 can be formed on dielectric coating 3 by chemical polymerization or electrolytic polymerization of a functional polymer layer made of e.g., polypyrrole or polythiophene. Solid electrolytic layer 4 can be also obtained by forming a manganese dioxide layer through impregnating manganese nitrate into dielectric coating 3 and pyrolytically decomposing it.

[0042] Further on solid electrolytic layer 4, collector layer 5, made by laminating only carbon layers or carbon layers together with conductive paste layers, is formed.

[0043] In this first embodiment, second connecting terminal 6 facing first connecting terminal 2 is formed on collector layer 5 by spattering gold. Another metal such as copper, nickel or tantalum instead of gold can be vapor-deposited or spattered. Collector layer 5 as it is can be utilized as the second connecting terminal.

[0044] The body formed hitherto is covered overall with insulating material, so that insulating section 7 is formed. Then hole 8 is formed, which extends through insulating section 7 on first connecting terminal 2 side and communicates with the first connecting terminal 2. Further, hole 9 is formed, which extends through insulating section 7 on first connecting terminal 2 side, first connecting terminal 2, porous valve metal sheet 1, dielectric coating 3, solid electrolytic layer 4 and collector layer 5, and communicates with second connecting terminal 6. Holes 8 and 9 are formed by etching, punching or laser processing.

[0045] On the inner wall of hole 9, insulating film 10 is formed by electro-deposition process of insulating material. Then conductive bodies 101 and 111 made from copper plate are formed in holes 8 and 9. Conductive body 101 in hole 8 is electrically conductive with only first connecting terminal 2, and conductive body 111 in hole 9 is electrically conductive with only second connecting terminal 6.

[0046] On the surfaces of conductive bodies 101 and 111, connecting bumps 12, made from solder, gold, tin or silver, are formed as surface connecting terminals, so that solid electrolytic capacitor element 200 is completed. A number of and a placement of connecting bumps correspond to those of the ICs to be mounted thereto. A number of bumps more than the number of the ICs can be formed because chip components such as a chip inductance can be mounted between remained bumps 12 after the mounting of the ICs. On insulating section 7 on the lateral faces and the bottom face of solid electrolytic capacitor element 200, outer terminal 13 coupled with the first connecting terminal 2 as well as outer terminal 14 coupled with the second connecting terminal 6 is formed.

[0047] Finally, electronic parts 16 such as chip-resistors, chip-ceramic capacitors, chip-inductances, ICs and the like are coupled with wiring patterns 15, so that a composite electronic component is produced. As such ICs 17 and the like can be mounted directly to one of the faces of the thin solid electrolytic capacitor, so that a conductive pattern for wiring is not needed. As a result, high-frequency response can be remarkably improved, and since the thin solid electrolytic capacitor is equipped with electronic circuit parts 16, a thin composite electronic component is obtainable.

[0048] In the first embodiment, an aluminum foil, of which one side has been etched, is used as porous valve metal sheet 1. Thus the aluminum foil of the aluminum electrolytic capacitor available in the market can be utilized. If a face of the aluminum foil is masked and then etched, porous valve metal sheet 1 having desirable etching pits on only one face can be obtained with ease. This method increases the productivity of the composite electronic components. When a sintered body of valve metal powder such as tantalum is used as porous valve metal sheet 1, a large electrostatic capacity can be obtained.

[0049] A use of one face of aluminum foil or sintered body of valve metal powder as first connecting terminal 2 saves a metal layer supposed to be a separate first connecting terminal, so that the productivity can be improved as well as the cost can be reduced. However, if the reliability of the connection between conductive bodies 101, 111 formed in holes 8, 9 and first connecting terminal 2 is desirably increased, first connecting terminal 2 is preferably formed by forming a metal layer of gold, copper or nickel on one face of sheet 1.

[0050] A use of functional polymers such as polypyrrole or polythiophene as solid electrolytic layer 4 produces a solid electrolytic capacitor having a lower impedance, which is excellent in high-frequency response. Forming manganese dioxide is an well established method, and this method allows elaborate control even over a thickness. A use of this method thus improves the productivity and reliability. Outer terminals 13, 14 are not always necessarily, and they can be replaced with connecting bumps 12 or wiring patterns 15. The ICs and chip parts mounted to connecting bumps 12 are used as leader-electrodes.

[0051] A method of manufacturing the solid electrolytic capacitor of the present invention is demonstrated hereinafter with reference to the accompanying drawings. First, as shown in FIG. 3, prepare an aluminum foil, of which one face has been etched, as porous valve metal sheet 1. This aluminum foil is obtainable with ease by masking one face before the etching process. In FIG. 3, etched shape to be formed on sheet 1 is omitted.

[0052] Next, as shown in FIG. 4, on the unetched face of sheet 1, form first connecting terminal 2 made from copper by spattering. Terminal 2 can be also formed by vapor-deposition or sticking copper foil to the unetched face.

[0053] Then as shown in FIG. 5, cover sheet 1 except the etched face with thermosetting polyester resin, thereby forming insulating section 7.

[0054] In this first embodiment, molding resin made of thermosetting epoxy resin and inorganic filler is transfer-molded, thereby forming insulating section 7. Instead of the thermosetting epoxy resin, photo-curable epoxy resin, thermosetting or photo-curable unsaturated polyester resin can be used as insulating resin. A method of application can be used instead of the transfer-molding method.

[0055] Next, anodize metal aluminum in forming solution to form dielectric coating 3 on the surface of the metal as shown in FIG. 6. Then dip the metal into solution including pyrrole, and then dip it into oxidizing solution, so that thin polypyrrole film is formed on dielectric coating 3 due to chemical oxidation polymerization. After the formation of polypyrrole thin film, dip the metal aluminum into solution containing pyrrole, and use the polypyrrole layer as an anode side and an electrode in the solution as a cathode side for performing electrolytic polymerization. This electrolytic polymerization forms polypyrrole layer having enough thickness on the thin polypyrrole layer. Solid electrolytic layer 4 is thus produced.

[0056] Next, as shown in FIG. 7, apply carbon ink on solid electrolytic layer 3 and dry the carbon ink, then apply silver paint and harden the silver paint, thereby forming collector layer 5 made of carbon layer and silver paint layer. Then as shown in FIG. 8, punch through-holes 9 at necessary places.

[0057] Next, as shown in FIG. 9, stick second connecting terminal 6 made of copper to collector layer 5 so that terminal 6 is electrically conductive with collector layer 5. Then as shown in FIG. 10, extend insulating section 7 made of thermosetting epoxy resin such that it covers second connecting terminal 6, solid electrolytic layer 4 and the surface of collector layer 5. As a result, the entire body is covered by insulating section 7. After that, as shown in FIG. 11, form insulating film 10 made of resin on the inner wall of hole 9 by electrode-position process.

[0058] As shown in FIG. 12, form hole 8 by laser process at a predetermined place on terminal 2, and form openings 52, 53 communicating with lateral faces of first terminal 2, second terminal 6 respectively. Then form conductive bodies 101, 111, 121 and 131 made from copper plate in holes 8, 9 and openings 52, 53 respectively. Conductive body 101 in hole 8 and conductive body 121 in opening 52 are electrically coupled with first connecting terminal 2. Conductive body 111 in hole 9 and conductive body 131 in hole 53 are electrically coupled with second connecting terminal 6.

[0059] Further, as shown in FIG. 14, form surface connecting terminals 12, i.e. connecting bumps made from solder, gold or silver, on the surfaces of conductive bodies 101 and 111, thereby completing solid electrolytic capacitor element 200.

[0060] Then as shown in FIG. 15, form outer terminals 13, 14 coupled with first connecting terminal 2 and second connecting terminal 6 via conductive bodies 121, 131 respectively on the lateral faces and the bottom face of capacitor element 200.

[0061] Next, as shown in FIG. 16, form wiring pattern 15, made of conductive material and corresponding to a circuit pattern, on insulating section 7 on which connecting bumps 12 have been formed. Then connect electronic components 16 including an inductance, resistors and the like as well as IC 17 to given places, thereby producing a composite electronic component.

[0062] The present invention allows to substantially lower the inductance of an electrical path between the capacitor and the IC, thereby improving high-frequency properties.

[0063] Exemplary Embodiment 2

[0064] In the second embodiment, valve metal powder is used instead of etched aluminum sheet. As shown in FIG. 17, sintered body 19 of tantalum is coupled with one face of tantalum foil 18, thereby forming porous valve metal sheet 1. The steps of forming insulating section 7 and onward, in other words, the steps shown in FIG. 5 and onward, are the same as those demonstrated in the first embodiment. A solid electrolytic capacitor is thus formed, and then a composite electronic component is produced.

[0065] In the first embodiment, as shown in FIG. 4, first connecting terminal 2 made from copper is formed by spattering on the unetched face of metal sheet 1 made from aluminum foil. In this second embodiment, first connecting terminal 2 made from copper is formed by spattering on the one face, where no sintered body 19 of tantalum is formed, of tantalum foil 18 shown in FIG. 17. The steps shown in FIG. 5 and onward are the same as those demonstrated in the first embodiment.

[0066] The completed composite electronic component has a dielectric, i.e., tantalum oxide, of which dielectric constant is greater than that of aluminum oxide, thus the composite electronic component features not only excellent high-frequency response but also a capacitor having a greater capacity. The sintered body of tantalum is formed of tantalum particles, which can be finely divided for enlarging an effective area of the capacitor. Therefore, this structure allows to increase both the dielectric constant and the capacity. As a result, the capacity as much as four times greater than using the etched aluminum foil is obtainable.

[0067] Exemplary Embodiment 3

[0068] Instead of using etched aluminum sheet, another valve metal powder than the second embodiment is used in this third embodiment with reference to FIG. 18. First, sinter the metal powder of tantalum and form porous tantalum sheet 19. Second, form insulating section 7 made of thermosetting epoxy resin on one face of sheet 19. Next, anodize sheet 19 including insulating section 7, thereby forming a dielectric layer overall the holes of porous sheet 19. The steps after this are the same as those in the first embodiment, i.e., the steps shown in FIG. 6 and onward. A solid electrolytic capacitor is thus formed, and finally a composite electronic component is produced. In this third embodiment, the sintered body has metal face 29 having been covered by thermosetting resin, and face 29 is not anodized but maintains electric conductivity.

[0069] First connecting terminal 2 made from copper can be formed by spattering on metal face 29, where no dielectric layer of tantalum sintered body 19 is formed, and insulating section 7 can be formed on terminal 2. The steps after the anodizing are the same as those demonstrated in the first embodiment.

[0070] The completed composite electronic component has a dielectric, i.e., tantalum oxide, of which dielectric constant is greater than aluminum oxide, thus the composite electronic component features not only excellent high-frequency response but also a capacitor having a greater capacity. Further, since this structure does not employ metal sheet, a thinner composite electronic component is obtainable.

INDUSTRIAL APPLICABILITY

[0071] The present invention relates to a composite electronic component to be used in various electronic apparatuses. According to the structure of the present invention, electronic parts are placed on a thin capacitor, so that ICs can be directly connected to one face of the thin capacitor. On the face, a connecting section is formed. Further, other parts can be mounted to the face, thereby forming a thin composite electronic component useful for preparing a digital circuit as well as excellent in high-frequency response. 

1. A composite electronic component comprising: (A) a capacitor element (200) including; (a) a porous valve metal sheet (1) of which first face has porous surface and dielectric coating (3) formed on the porous surface; (b) a first connecting terminal (2) provided to a second face of the porous valve metal sheet (1); (c) a solid electrolytic layer (4) formed on the dielectric coating (3); (d) a second connecting terminal (6) formed on the solid electrolytic layer (4); (e) an insulating section (7) formed on the valve metal sheet (1), the first connecting terminal (2) and the second connecting terminal (6); (f) a first hole (8) extending through the insulating section (7) and communicating with the first connecting terminal (2); (g) a second hole (9) extending through the insulating section (7) and the valve metal sheet (1), and communicating with the second connecting terminal (6), and having insulating film thereinside; and (h) conductive bodies (101, 111) formed in the first hole (8) and the second hole (9) respectively, the bodies (101, 111) being electrically coupled with the first and second connecting terminals (2, 6) respectively and being insulated from other sections; (B) a surface connecting terminal (12) provided to at least one face of the insulating section (7) and electrically coupled with the capacitor element (200); (C) a plurality of wiring patterns (15) provided to the same face as the surface connecting terminal (12); and (D) outer terminals (13, 14) electrically coupled with the capacitor element (200) at a lateral face of the insulating section (7).
 2. The composite electronic component of claim 1 further comprising collector (5) between the second connecting terminal (6) and the solid electrolytic layer (4).
 3. The composite electronic component of claim 1, wherein the porous valve metal sheet (1) is made from aluminum foil of which one face is etched.
 4. The composite electronic component of claim 1, wherein the porous valve metal sheet (1) is made from sintered body (19) of valve metal powder.
 5. The composite electronic component of claim 1, wherein the porous valve metal sheet (1) is made of valve metal sheet (18) on which sintered body of the valve metal is formed.
 6. The composite electronic component of claim 1, wherein the first connecting terminal (2) is a first face of aluminum foil of which second face is porous due to etching process.
 7. The composite electronic component of claim 1, wherein the first connecting terminal (2) is another metal layer formed on a first face of aluminum foil of which second face is porous due to etching process.
 8. The composite electronic component of claim 1, wherein the first connecting terminal (2) is a face (29) of the valve metal sheet (1) made of a sintered body of valve metal powder, the face (29) having no dielectric.
 9. The composite electronic component of claim 1, wherein the first connecting terminal (2) is another metal layer formed on a face (29) of the valve metal sheet (1) made of a sintered body of valve metal powder, the face (29) having no dielectric.
 10. The composite electronic component of claim 1, wherein the first connecting terminal (2) is a first face of valve metal sheet (18), on which second face a sintered body of valve metal powder is formed.
 11. The composite electronic component of claim 1, wherein the first connecting terminal (2) is another metal layer formed on a first face of valve metal sheet (18), on which second face a sintered body of valve metal powder is formed.
 12. The composite electronic component of claim 1, wherein the solid electrolytic layer (4) employs functional polymer.
 13. The composite electronic component of claim 1, wherein the solid electrolytic layer (4) employs manganese dioxide.
 14. The composite electronic component of claim 1, wherein a number of the surface connecting terminals (12) is greater than a number of connecting bumps of an integrated circuit. 